Clutch



bers is substantially reduced as compared Patented Dec. 7, ,1943 ICLUTCH .101m 'Mlnoawelr shawbridge, Quebec, Canada.,

assigner of one-half to Paul C. Jones, Montreal,

Quebec, Canada Application October 7, 1941, Serial No. 414,024l

.13 Claims.

This invention relates to clutches of the type generally known asfree-wheeling or overrunning clutches. Such clutches are used forcoupling together the driving and driven shafts of an internalcombustion engine starting mechanism and in various other relations.'The ivmproved clutch provided in accordance with this invention isadapted for use in all cases where an efficient free-wheeling" clutch isrequired. y

An important object of the invention is to provide an eicientfree-wheelingrclutch in which the metal-to-metal contact largelyresponsible for the noisy operation and excessive wear characteristic ofthe free-wheeling clutches` now in use is completely eliminated.

Another object is the provision of a free-wheelstresses imposed on' thecomponent vparts of the clutch by the establishment of a. drivingconnection between the driving and'driven clutch I nemthe free-wheelingclutches now in use.

A further object is the provision of a-freewheeling clutch which is notonly quieter in pp.- eration and less subject vto wear and jamming ascompared with the free-wheeling clutches now in use but is alsoconsiderably more economical as regards production, installation andmaintenance' costs.

A further object is the provision of afreewheeling clutch includingmeans for preventing damage due to over-loading. For example, in thecoupling together the driving and driven shafts ,of the startingmechanism of an internal combustion Iengine it is desirable thatover-load renent parts of the free-'wheeling clutch, of the destructiveover-load.to which such parts might otherwise be'subjected, incaseofengine backfire. The safety or over-loadrelease feature here referredto is also of advantage in that it extends the normal life of all partsofthe clutch and .starter mechanism to a very considerable extent ascompared with the use of free-wheeling clutches in which no provision ismade for preventing dcstructive over-loading in case of engine back-tireor other causes of over-loading.

'Ihe foregoing and other objects, as well as the with .ing clutch inwhich th'e severity of the shock characteristic features of theinvention will be more readily'understood from the following detaileddescription taken in connection with the accompanying drawing- Fig. 1 isa vertical sectional View of my im-A proired clutch.

' ,Elg. 2 is a sectional view. taken along the line 2-2 of Fig. 1.

Fig. 3 is a fragmentary perspective view of the clutching element.

Fig. 4 is a detail view showing a modication of the anchoring means forsecuring ,the clutching element to the driven clutch member.

Fig. 5 is a detail view showing a component elementl of the anchoragemeans disclosed in Fig. 4.

Fig. 6 is a side elevation of the clutching element vas itappears in itsnormally straight condition and 4 Fig. '7 is a transverse sectional viewtaken along the line 1-1 of Fig. 6.

As shown in the drawing my improved clutch comprises a male clutchmember 5 fixed to rocase of a free-wheeling clutch which is used fortate with a driving shaft 6, 'a female clutch member v1 fixed to rotatewith a driven shaft 8 and a non-metallic clutching element 9 arrangedwithin anjenclosedL annular space l0 formed by and between the clutchmembers 5 and 1 when the latter are assembled in the intertting re'-lation shown in Figs. l and 2.

The male clutch member 5 is shown as a collar fixed to one end of thehollow driving shaft 6.` This member carries the clutching element A 9which consists of a relatively long and narrow strip of flexible-andfreely elastic material such as rubber;L said strip being expansibleincross section when subjected to longitudinal compression and havingincorporated therein a series of reinforcing cords l I which limit thelongitudinal i stretch of the strip. As shownlin Figs. 6 and '7 thestrip A9 is normally straight and is trans- ,versely curved in crosssection, Vthe upper surface of the strip being convexlycurved asindicated at 9c and the lower surface being concavely curved asindicated at 9d. When in use the strip 9 is bent or curved to extendaround the majorportion of the periphery of the memlber 5 and has oneend fastened toy an anchoring key l2 provided with a dove-tail shapedportion l2a which is slidablyandlemovably tted in a groove I3 providedin member 5. When the strip 9 is thus bent or curved around the member 5the transversely curv/ed surfaces 9c and 9d are straightened orflattened out to give the nat rectangular cross sectional contour shownin -inner periphery of the strip while the surfacev 3c forms the outerperiphery of the strip. In this connection it may be explained that ifthe surfaces 9c and 9d of the strip were fiat in the straight positionof the strip illustrated in Fig. 6

the surface 9c would be caused to assumea concave transverse curvatureand the surface 9d would be caused to assume a convex transversecurvature by the bending or curving of the strip around the member 5. Inthe driving condition of the clutch it is important that the entirewidth and sides of the strip 9 be inv driving contact with the clutchmembers 5 and 1 and this, of course, means that the inner and outerperipheral surfaces and sides of the curved strip must be perfectly fiatacross their entire width. This is assured by'forming the strip so thatthe surfaces 5c and 8d are transversely curved when the strip is in thestraight condition shown in Fig. 6 but are flattened out when the stripis bent to theV 'substantially circular form shown in Figs. l and 2. Inthis connection it will also be noted that when the strip 9 is in thenormal straight or Iout-stretched position shown in Figs. 6 and 'I thesides of the strip are inclined so that, if

is arranged in the inwardly facing channel afforded bythe side andperipheral walls of the casing I5 so that the dovertail shaped portionI2a ofthe key projects inwardly beyond the inner edge of the walls I8.The clutch member 5 is then fitted in the member 1 so that during thisassembly the dove-tail portion I2a of the key I2 is received in theAgroove I3. The clutch member 5 is then secured in place by a ringshapedfacing plate 20, which is screwed into the outer portion of the flange1b as indicated at 2|, said facing plate being provided with a centralopening 22 for the passageof the driving shaft 3, said opening beinglarger than the shaft toy provide clearance.

A thrust washer 25 is interposed between the end wall 1a of member 1 andthe adjacent side of the clutch member 5 and a similar thrust washer 25is interposed between the opposite side of the clutch member 5 and theface plate 20. The washers 25 and 26 are slightly thicker than the wallsI6 and I8 of' casing I5 and provided with beveled edges 29 and 30 whichserve, in con- Junction with the bevelled edges 3| and 32 of said wallsI6 and I8 to guide or deflect lubricating oil outwardly through the oilexhaust openings 33 to imaginary converging lines 9x are drawn from`these sides, they will meet at a point 9g which is located about 2% fromthe centre of the strip' and which coincides with a centre of curvaturecommon to both the curved surfaces 9c and 9d. During the bending of thestrip 9 to the substantially circular form shown in Figs. 1 and 2 thesides of the strip become parallel to each other and parallel to theopposing side walls of the enclosed space III.

' 'I'he length and stretchability of the strip 9 is such that, when thisstrip is stretched to the maximum -extent permitted .by the stretchcontrolling cords II, the free end of the strip, which is preferablythickened as indicated at 9a, will be spaced an appreciable distancefromthe strip anchoring key I2. When the clutch is at rest or isfree-wheeling the strip 9 does not entirely fill the annular space I Iiformed by and between the members 5 and 1 but the amount of clearanceshould be exceedingly small.

The driven member 1 is a drum-shaped member presenting an end wall 1aand a peripheral ange 1b. This member carries an annular channel shapedcasing I5 which is a push-fit therein. As here shown casing I5 includesan inner side wall I5 which is a close fit against the end wall 1a ofmember 1, a peripheral wall I1 which is a tight or push-fit against theinner surface of the flange 1b of member 1 and an outer side wall I5which is located inwardly with reference to the free edge of flange 1b.The width of the wall I5 of casing I5 is such that the inner diameter ofthis wall is less than the diameter of the clutch member 5. The width of[the wall I8 of casing I5 is such that the inner diameter of this wallis very slightly greater than the diameter of the clutch memberi. Thispermits the clutch member 5 to. be slipped inwardly through the openingbounded by the in ner edge of the wall I8 when the clutch members 5 and1 are being assembled in the interfltting relation shown in the drawing.It may be pointed out here that, priorv to theassembly of the clutchmembers 5 and 1 in their interiitting relationythe clutching element orstrip 9 with the key I2 and nbre inserts attached thereto prevent suchoil being thrown to thepe'riphery of the clutch member 5 and intocontact with the clutching element or strip 9. vIf desired, an oilretaining ring 34 of any suitable material may ,be arranged between thebevelled edge 2B of the thrust washer 25 and the Opposing bevelled edge3| of wall I6 and a similar ring 35 may be arranged between the bevellededge 30 of the thrust washer 26 and the bevelled edge 32 of wall I8.

. 'I'he driven shaft 8 carries a bushing 31 which extends into and is arotatable fit in the hollow driving shaft 6. This bushing serves as acentral aligning bearing which holds the shafts 8 and 6 in alignmentandserves to prevent wobbling of the male clutch member 5 with reference tothe female clutch member 1. In this conthe desired clearance between theclutching element 5 Aand the'female clutch member 1. When the clutch isat rest or is free-wheeling correct alignment of the clutch members isalso necessary to ensure etlicient operation of the clutch.

As will be evident from the foregoing description the side and outerperipheraLwalls of the space III in which clutch strip 9 is housed areformed respectively by the side walls I6 and I8 and the peripheral wallI8 of casing I5, the inner peripheral wall of saidlspace being formed bythe periphery of the driving member 5 with which the strip 3 is normallyin contact except at its free end. When strip 9 is in relaxed or normalcondition it is clear of contact with the side and outer peripheralwalls of the enclosed space I0 except at the extreme free end of thestrip where contact is made with the outer peripheral wall of the casingI 5 as shown to advantage in Fig. 2. If we assume that shafts 5 and 8are Vrotating in the same direction as indicated by the arrow X and thatshaft a is turning faster than shaft s there will be a drag exerted onthe free end of the clutching strip 9 which, in addition to a slighttendency to stretch the strip, will tend to wind it more closely aroundthe driving member 5 with the-result that said strip offers practicallyno resistance to the turning of the clutchmember 1 relative to theclutching member 5. This is the free-wheeling condition. On the otherhand if the driving clutch member 5 is turned in the didriven clutchmember 5. This longitudinal compression of the strip 9 causes it to beshortened and, at the same time, to be expanded laterally p tocompletely ll the cross sectional area of the enclosing space I0. Inother words, as the strip- 9 is compressed the material thereofflowsradially and laterally to fill thespace I and thus establish apositive driving connection between the driving clutch member yand thedriven clutch member 1. If, subsequent to the establishment of thisdriving connection the torque load on the clutch increases beyond apredetermined value,

the casing I5 will turn as a unit with the member 5 and the strip 9relative to the driven clutch member 1 to prevent damage due to suchoverload. Another advantage 'of the construction described herein isthat the resilient compressibility of the clutch strip 9 givessufficient cushioning action during the establishment of the drivingconnection between the clutch members y 3 sion between the clutchmembers 5 and 1 the lateral' expansion ai; the anchored end of the stripcauses the inserts 39 to move outwardly against the opposing walls ofthe space 'I0. While I have stated that the insertsl 39 are preferablymade of bre,they` may be made of any other suitable material.

In Fig. 2 I have shown'a pinch roller III interposed between theclutchmember5 and the strip 9 at'a point adjacent the free end of thestrip. The roller 4I works in a peripheral recess 42 the bottom wall 43of which is inclined so that the roller -4I approaches the peripheralwall I1 ofcasing I5 when said roller is displaced in a vclockwisedirection relative to the member 5 when the latter'is rotated in acounter-clockwisedirection as viewed in Fig. 2. The free end 9a rofvstrip 9 is somewhat thicker as compared with the remainder of the stripso as to cooperate more effectively with the roller 4I.

Assuming that, the clutch member I is at rest and that the clutch member5 is turned in the lengthwise compression and lateral 'expansion of theclutch member 9 and that the driven clutch member 1 is now commencing tooverrun the driving clutch member 5. As soon as this condition obtainsthe strip 9 is relieved of lengthwise compression and, due to itsinherent resiliency, immediately springs back to its normal full lengthrelaxed orcontracted condition so that the driving connection previouslyestablished between the clutch members is thus immediately relieved andwithout any tendency to sticking as soonas the driven clutch membercommences to overrun the driving clutch member. `As a matter of factthis immediate elastic return of the clutch strip 9 to its clutchdisengaging condition vis assisted by the dragging and stretching actionwhich the clutch member 1` exerts against the strip 9 underfree-wheeling conditions.

It is desirable, during the longitudinal coin-I pression and lateralexpansion of the strip 9, to-

prevent ow or displacement of the material of the strip into theclearance spaces reserved between the strip anchoring key I2 and thewalls I6, I1 and I8 of casing I 5. In practice it has been foundthat ifAthe material of the strip 9 is permitted to be displaced into theseclearance spaces there is apt to be some shearing of the dis'- placedmaterial between the edges of the key I2 and the said walls of thecasing I5.

' aforesaid clearance spaces, do not interfere with the lateralexpansion of the anchored end of the s'trip during the establishment ofa drive connection between the clutch members 5 and 1. When the strip 9is subjected to longitudinal compresdirection indicated by the arrow Xthe said member 5 will have a slight initial relative movementwith.respect to both the roller di and the free end 9a of the stripsince the said free end of the strip is held back by its contact withthe wall I1 of casing l5.v This relative movement between the member 5and the roller 4I causes the latter to be forced outwardly against theadjacent, portion of the strip 9 and to press the latter tightly againstthe wall I 1. This ensures that the whole length of the strip 9 lyingbetween the key I2 and the roller 4I will be uniformly expanded intotight frictional engagement with the defining walls of the enclosedspace I0. The action of the parts is also such that the roller 4I tendsto become wedged between theinclined bottom wall I3 of the recess 42 andthe thickened end 9a of the strip 9, but unwedges readilyandautomatically rolls back to original position when rubber strip 9expands in overrunning condition.

A portion of the periphery of the Amember 5 is cut away between the keyI2 and the recess d2 to ensure a certain amount of clearance betweenthis portion of the member 5 and the end por-v tion of the strip 9 whichprojects beyond the roller EI. If desired the roller 4I may be replacedby some form of rocker member or other device which will give the sameresults.

'The casing I5, while constituting an important safe-guard against.damage to the component parts of the clutch in case of jamming or over-In order to vprevent this fibre inserts 39 are inlaid in the loading,;isnot an absolutely essential feature of the invention and may bedispensed with if desired. In this 'connection it will be understoodthat,- when the casing I5 is omitted, the side and outer peripheralwalls of the annular space I0 will be constituted by the end wall 1a andflange 1b of member 1 and by the inner side of the face plateA 29.In-this latter event the dimensions of the clutch will, of course, bechanged so that the required small clearance will be providedbetween thestrip 9 and the wall members forming the side and outer peripheral/portions of the space IIJ.

It is important that the nbre inserts 39 be' securely fastened to thestrip 9 andthat the latter be securely anchored to the key I 2 to avoidseparation of these parts in seryice'. This, how--l will prevent theseparts becoming detached in lservice. y

In Figs. 4 and 5 I have shown a vmodiilcation in whichV the stretchcontrolling cords Il,` oi' the strip 9 are extended beyond the keyengaging end of the strip and are clamped in place between the parts 41and 48 of a two-part key generally indicated at 49, the part 41 of saidkey being provided with suitable cord receiving grooves 50. This form ofkey is preferably provided with straight sides and is removably securedin the groove I3 of member 5 by a suitable fastening screw 5I. Variousother methods of anchoring the strip 9 to the member 5 may also beresorted to. l

The iibre inserts 3,9 are preferably vulcanized to the strip 9 duringmolding or forming of the latter but may be secured in place in anyother suitable manner. l

It may also be pointed out that it is not absolutely essential to thisinvention that the strip s 9 be anchored to the member 5. On thecontrary, the strip 9 may be arranged with one end anchored to theperipheral portion of the mem- .ber l and the inner .or free-enddisposed to en- Y-gage the peripheral portion of the member 5.

In this case the roller 4|, if used, will be-interposed between theperipheral portion of the member 1 and the strip 9 adjacent the free endof the latter. So far as the actual operation is concerned, it isimmaterial for many purposes. whether the female member 1 or male member5 constitute the driving member of the clutch.

In addition to the specic modifications mentioned herein it iscontemplated that various other changes in the construction andarrangement of the -parts may be resorted to Within the scope or spiritof the invention as defined by the appended claims. Y

Having thus described my invention, what I claim is:

asada-is two-part key is fitted in a peripheral recess pro vided in thedrivingclutch member and in which the clutching element is provided witha plurality of stretch controlling cords which extend the full length ofsaid element and project beyond the anchored end thereof, the projectingends of said cords being clamped in .place between the two parts of saidkey.

'7. A clutch as set forth in claim l, in which a key is carried by thedriving clutch member and projects beyond the periphery of said clutchmember and in which the anchored end of said clutching element isvsecured to said key, said clutching element being provided with hardinserts inlaid in the side and outer peripheral portions thereofimmediately adjacent said key, said inserts serving to prevent crowdingof the elastic material of the clutching element into clearance spacesreserved between the key and the side and outer peripheral walls of saidenclosed 'cooperating with said enlarged end to force the clutchingelement outwardly against the driving clutch member in response tomovement of the driving clutch member relative to the clutching elementin the direction of the free end of the 1. A free-wheeling" clutchcomprising rotary 1 driving and driven clutch members rotatable about acommon' axis and fitted together to provide an enclosed annular spaceencircling said axis,a clutching element arranged within said enclosedspace and comprising a strip of material which is flexible, freelyelastic and Aexpansible in cross section, one end of said strip bein-ganchored to the driving 'clutch member and the other end being free anddisposed in contact with the driven clutch member, the cross sectionalarea of said strip being slightly less than the cross sectional areaofsaid enclosed space when the clutch is at rest or is free-wheeling butbeing increased, by longitudinal compression of the strip between saidclutch members to fill said enclosed space, when the driving clutchmember to which the strip is attached is and in the direction of thefree end of the strip.

2. A free-wheeling" clutch as set forth in claim 1 including meansinterposed between the driving clutch member and said strip for forcingsaid strip outwardly against the driven clutch member in response tomovement of the driving y clutch member relative to said strip and inthe direction of the free end of the strip.

3. A clutch as set forth in claim 1 in which the driven clutch membercomprises two parts,

. only one of which is engaged by the clutching element, said partsbeing fitted together so that they normally rotate as a unit' but arefree to rotate relatively to each other under predetermined conditionsof overload.

latter. l l

9. -A clutch as set forth in claim 41, in which thrust washers areinterposed between opposing side portions of the driving and drivenclutch members and serve to hold the clutching element in spacedrelation to the side walls of said enclosed space when the clutch is atrest or is free-wheeling, said thrust washers being provided withbevelled edg opposed to corresponding inclined bevelled edges presentedby portions of the driven clutch member, said bevelled edges beinglocated intermediate the inner and outer periphery. of the drivingclutch member and serving as oil deiiecting guides to prevent oil beingthrown from the inner tothe outer periphery of the driving clutch memberand into contact with the clutching element.

10. A clutch as set forth in claim 1, in which thrust washers areinterposed between opposing side portions of the driving and drivenclutch members and serve to hold the clutching element in spacedrelation to the side walls ofsaid enclosed space when the clutch is atrestor is freewheeling, said thrust washers being provided with bevellededges opposed to corresponding inclined bevelled edges presented byportions of the driven clutch member, said beveled edges being locatedintermediate the inner and outer periphery of the driving clutch memberand serving as oil deiiecting `guides to prevent oil being thrown fromthe inner` to the outer periphery of the driving clutch member and intocontact member being provided with-oil exhaust holes y of said clutchmember.

12. A clutch as set forth in claim 1 in which the driven clutchmembercomprisesan outer casing including an end wall and a peripheral- 1`5ment at all times.

flange andan inner casing including a periph- Y eral wall and sideanges, the peripheral wall of the inner casing being a push-fit in theperipheral ilange of the outer casing, at least one of .the side angesof said inner casing being dimensioned so that its inwardly facing edge,describes a circle whose diameter is slightly greater than the outerdiameter of the driving clutch member. v

13. -A free-wheeling clutch as set forth in claim 1 including a centralaligning bearing by means of which the relatively rotatable parts of theclutch assembly are maintained in correct align- JOHN M. oDwELL.

